Open Lung Maneuvers During High Frequency Oscillatory Ventilation in Preterm Infants

Background: Open lung maneuvers aim to recruit and stabilize the majority of collapsed alveoli, using oxygenation as an indirect variable for lung volume. The stepwise oxygenation-guided lung recruitment procedure during frequency oscillatory ventilation (HFOV) in preterm infants has a low risk of lung hyperinflation and air leak syndrome. Nevertheless, open lung maneuvers at regular intervals during HFOV to maintain or restore oxygenation is not implemented as a routine procedure in the neonatal intensive care.

Aim of the study: To assess whether stepwise oxygenation-guided lung recruitment at regular intervals reduces the oxygen saturation index (OSI = Mean Airway Pressure × Fraction of inspired Oxygen × 100 / peripheral Oxygen Saturation, OSI = MAPxFiO2x100/SpO2) averaged over HFOV time in extremely preterm infants.

Study design: Single center randomized controlled study.

Methods: Thirty-six extremely preterm infants below 28 weeks of gestational age and on high frequency oscillation ventilation receive either stepwise oxygenation-guided lung recruitment maneuver at regular intervals (intervention) and upon decision of the care giving team (intervention group) or lung recruitment maneuver only upon decision of the care giving team (standard, control group). The primary outcome is the oxygen saturation index averaged over HFO ventilation time. The observation time of the HFOV will be limited to at most seven days.

Sample size: Fifteen infants need to be enrolled in each group to have 80% power (at a two-sided alpha level of 5%) to detect a difference of 25% in the oxygen saturation index between the intervention group and the control group.

Main outcome variables: Oxygen saturation index averaged over HFO ventilation time.

Secondary outcome variables: Bronchopulmonary dysplasia (BPD); days of ventilation; oxygen saturation index averaged over ventilation time (HFO and conventional ventilation); the following variables measured before, during and after a single stepwise oxygenation-guided recruitment maneuver: echocardiographic parameters, reactance, relative impedance changes, lung ultrasound measurements, transcutaneous partial carbon dioxide (CO2), blood pressure, heart rate.

Inclusion criteria

Preterm infants

• born below 28 weeks of gestational age
• not older than 29 weeks of postmenstrual age
• receive HFOV

Exclusion criteria

• known congenital anomalies of the heart, of the lung, and/or of the central nervous system
• known chromosomal abnormalities
• participation in other intervention trials